I am trying to recreate a nautical map, which all the makers flashing the correct sequences. I have manged to split all 200 into 18 categories (one per pin), some pins only have 4/5 Leds, but some have 25 or so.
I know I need to buy some MOSFET transistors, but just need some advice on which ones to buy and will I need a battery per transistor, or can I wire one battery in parallel across a couple of transistors.
Which Arduino are you using?
use adressable LEDs - then you can drive the 200 individually and don't need tons of pins.
What LEDs? What is their forward voltage, and what current do you want each led to receive? Knowing that, we can recommend suitable MOSFETs.
You can use one battery for all your LEDs, if it has a suitable voltage and current. For example a car battery will provide about 12V and a huge current. Other, smaller types of Sealed Lead-Acid (SLA) batteries such as those used in burglar alarms could also be used.
An advantage of using higher voltage batteries is that you can connect several LEDs in series which means they share the same current, and fewer current limiting resistors are needed.
Here is a useful on-line calculator that will suggest different ways to wire your groups of LEDs, what value series resistors will be needed, and the total current the group will draw.
https://www.hebeiltd.com.cn/calculator/v5/led.php
For example for your group of 25 LEDs, assuming they have a forward voltage of 1.8V and you want 20mA of current:
I think I would prefer solution 1 above, over solution 0, because all the resistors are the same value and wattage.
You could also consider using TPIC6B595 shift registers. Not only would these save you lots of Arduino pins, but each chip has 8 MOSFETs built-in, making your design much simpler.
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